The Collaborative International Dictionary of English v.0.48:

Celestine \Cel"es*tine\, Celestite \Cel"es*tite\,, n. [LL.
   caelestinus bine.] (Min.)
   Native strontium sulphate, a mineral so named from its
   occasional delicate blue color. It occurs crystallized, also
   in compact massive and fibrous forms.
   [1913 Webster] Celestine

WordNet (r) 3.0 (2006):

celestite
    n 1: a mineral consisting of strontium sulphate